Method of making cockle paper



Jan. 25, 1949.

s. B. STAFFORD METHOD OF MAKING COCKLE PAPER Filed Jan. 13, 1945 5%}:Han BSTQHQWL Gttomeg Patented Jan. 25, 1949 ice B rton-Cnrnq tim, pr eie r Mass, a ..eormnafibnofMass ts ApplicationfJanuarir-13, 1945, SerialNo. 572,711 teams. (01. iii-+11) .1 inventio r la e t atmethcrl oi m kinwels -Pa erer eo lsl a e ha been-"m denb aak plume eo kle b izi asi mg49 a panel" Web ifed eentinuous y from a su ly T011": and-there fte 19%thi W bpmere s dr hrou a dry n her-wherein the paper is hung-in festoonson erosshars or so-called stiekswhieh are meved for- V wa d me hani llafte th nap h bee un ethereen -'l?he-wet pa e -han wi h the $1111Meightpie eh loo sus e d dfro -th a i n where ere s biee edl t di p qthepa e e d b ut-out'ans carde :Ehi e uire -tu pa e i t i a e heet andns in h m and csgrting I out. the defe tive mark ereafter therejeetedsheets-are a ga asrnaller size and inspected andsorted-once'more. involves not only' a hi h labor charge butparticularly aver-y largewaste of paper.

It has also been attempted to dry that sized paper passing itback andforth over 'a-series elf-positively driven'rolls, but, these rolls-puttension Orr-the :paper whichtend'to pull out the eoekle-efiect andthus-to smoothcut the paper. The cockleappearanee is caused. inv part bythe uneven, shrinkage of the paper pulp fibres whereinn they tend tocurl andmove somewhat durin 'the-.;drying operation, endthis isneateriallzs"v aided by he sizing Which-in shrinkage-tends to distortthepaperinto a bumpy and locally wrinkled apggearance It is found thatany attemptatmaking eeekl ap -b -method twhicn pu te sie nthe paper stin inwet st e t nds to.:. royh. eeek esl-izeee ii n an thu defea th pr mry ab Ml ee 1m s hi inrentiqe-i iem ke re b i en een' ln t eape w th asuitable sizing and then drying the paper under sueh eonditions that, itisnot subjectedto amate- Fia ee d e sio an t ee teq -withsupth dryin(aera on ml i i d o d-:0ck1e;- fie a;-P dwitho A a aa Eurthe p le swfl eap arm-inthe ellew ee s e nr @3 to-the draw n ,a arethe illus, tsetse-"ereie re mnstru tion ape leof-earryla eutmr me eda h e Fig; 3iss-ravverticalgtransverse;sectiontakens-ubst t ll-y-en the ine .3.--,3of Fi In accordancewith my preferred method,=a web of paper is, treatedwith a suitable animal or vegetable sizing material, sueh-as;g1ue,- starch,

a, oonvertedystaromsoy bean- Vflour, casein, .a syn-' thetic resin,various: cellulose; derivatives ormixtures ofthese, or other suitableadhesive coating materials inaan aqueous or other suitable evaporable.medium. This sizing-may be incorporated in, or applied tothe, paper invarious ways, such asby sprayin or flowing an aqueous-suspension orsolution of the. sizing on the surface of the paper. But I; prefer toimpregnate the paper -by feeding a vveb ofpaper lllprogressively from yaI supplyroll-ll or other-suitable sou-rcethrough a sizing bath lz ofanaqueous'solution of starch and gluein-eny;desiredproportions held in avat Band thenbetween massive pressurerolls l4 arrangedabove the vatwhiohremove the excess'of sizing: and Squeeze the rest into the paper. Theserolls serve also to draw the paper forward- .from the supply roll atauniform rate andxthus present it "progressively for the drying step.The paper strip isheld beneath thesurface: of the sizing by a-roll l5.

In, the drylng-zonethepaper is dried in a horizontal position bysuitably applied heat, and" is movedforwardunder a controlled lighttension. It may he moved by a suitable-conveyor, such as the ladder typeendless belt conveyor I6 which may-vslipzrelative to the paper as itfrietionally ,=;rips the. under surface thereof and thus not mark thepapenmaterially. In the preferredarrangement the paper issubjected to aheated air cur rentwh lethusmovins; nd th air-maybe reetedvagainstgtheunder side of the paper to give a-huoya-nt eitect that materiallyreduces'the stick marleing and thepressure: 01: contact of the paper onheeonveyon ;The:.-buoyantair current,-which ngayesuchgaste-float thepaperstrip partially or.suhstantially fully, is derived from aniair duct[8 arran ed: below onerunofthe conveyor; The .PQ DQI'aPQSSess throughthe drying zone in a substantialy'flateand' horizontal :position andunder aminimumtension. It. then travels .over a-set of guide rolls l9ands-20 which provide enough tenSiDn-inthe-idrypaper so it may besatisfacte fll Wound A on "ya! suitably driven winding spool ;,g1oi,1i'nthisswlet condition through the drying gzpne. an exaessiveten-sionwould tend to break This space is formed by the upper perforated wall 30of the duct l8 and the lowerp'e'rforated wall 32 of a further hot airduct 33. An impervious top wall 34 and suitable connecting side wallscomplete the upper duct 33. Thelowefduct I 8 has a solid wall 35 for itsbottom, and suitableconnecting side walls. The lower run of thecconveyorl6 passesbetween the wall 35 and a lower horizontal wall 36 spacedtherefrom. Side walls s1 and end walls 38 provide a substantially closedchamber for the dryer. The paper enters and leavesrthe drying chamberthrough theopenings 39 in theendwalls.

Heated air is conveyed to the upperand lower ducts" l8 and 33 above andbelow the run of the paper l0 by means of ducts 4B throughwhichair isblown by means of a-su itable driven fan 42 arranged to draw air througha heating zone, such as over a set of steam heated pipes 43. Althoughthe air may be recirculated, it is'shown as coming from the outsideatmosphere through an opening 44 in the wall of the heating compartment.The side ducts 40 receive heated air from a common duct 45 connectingwith' the fan chamber, and they project laterally and then upwardly oneach side of the drying'chamber where.

they communicate through lateral ducts 46 and 41 respectivelywith thelower and upper spaces I8 and 33 for delivering the heated air to thepaper. 3 These various passages and compartments are suitably arrangedso that the heated air is forced to travel only through the openingsinthe perforated walls'3flan'd' 32 into contact withthe paper 10. Theheated air may be exliausted to the outside atmosphere through ducts Inorder to adjust the relative amounts oi heated air passing into theupper'and lower ducts above and below the paper, I provide a pivotedflap damper 50 at the junction point between the smaller ducts 46 and41, and this is controlled by an outside handle 5| or other suitablemeans.

Figr3, the damper may be moved to a position where the major portion ofthe air goes into and through the lower duct [8 'andthus against theunderside of the paper. 'In the latter case, the pressure of the airbeneath the paper tends to iioat the paper above the conveyor l1, andthe air issuing through the top wall 32 does not provide. enoughpressure to force the paper downwardly to a material extent.

I The paper may be conveyed through the drying zone under a minimum" oftension'by the construction illustrated, in which the conveyor 16 is Iformed of cross bars or sticks 54 shaped ashollow metal tubes. A shaft56 fits into each'end of the metal tube and the outerend of each shaftis a bearing support for a roller 51. Each roller 5'! at :.theupper runof the conveyor rides on the rail 58 4 suitably carried by the walls ofthe drying apparatus. A further rail 55 supports the lower run of theconveyor. Chain links 68 connect the shafts 56 at each side of therollers and thus form an endless jointed ladder type of conveyor as willbe apparent. This endless conveyor is driven by any suitableconstruction, suchas the two pairs of gear shaped wheels 5| mounted oncross shafts 62 that are suitably driven, as by means of a pulley andbelt drivefiii connected with a source of power. The drive gears 6i haveteeth so spaced as to engage the rolls 5'? which. carry the cross bars54. V

I may also provide a supplemental carrier for the. paper at the exit endof the drying zone which may either cooperate with or replace theendless carrier above described. This supplei .ental carrier maycomprise an endless belt made of felt or canvas or other suitablematerial mounted on and moved by two rollers 63 suitably driven by powermechanism. In the construction illustrated in Fig. 1, the paper ill isshown as passing in a loop beneath that belt and not conveyed by it. Butthe paper may be fed across this endless belt 65, and because of thefrictional grip of the belt surface, the paper will be gently pulledalong. The belt 65 servesprimarily when the paper is fully supported onthe air currents derived from'the air duct l8. In that case, the paperis movedthrough the drying zone without an unnecessarily high tensionwhich would serve to break or injure the paper or to pull out the cocklethereof, since the only tension required is that slight amount requiredto hold the ends of the paper against'the force ofthe supporting aircurrent and to. move it along. Thisfrictionless support and conveyanceof the paper can be delicately controlled so that very thin paper may besafely transported and dried. V

In its mechanical operation, the construction as thus described, servesto draw the dry paper from the supply roll I! through the sizing bath 5?and thence between the power driven pressure rolls M which press thesizing material into the fibres and pores of the paper and squeeze offany surplus that does not impregnatethe paper. Then the paper is drawngently forward byrneans of the frictional grip of the cross sticks orbars 5 of the endless conveyor It as it is subjected, to the. hot aircurrentsirom ducts l8 and 23 arranged above and below the paper. Inorder that variations in speed of the supplemental winding apparatus maynot place any tension on the paper, the paper passes in a longself-supporting loop from the exit end of the drying apparatus to thero1lsfl9. As soon as the paper is fully dry, it may be wound onthespool' 22 without destroying the cookie, and the tight roll will keepout moisture'and insure that, the cockle will remain until the papercanbe cut into sheets andthen Wrapped in required sizes. V

A substantial portion of theweight of thepaper is supported on the aircurrents issuing from the lower air duct I8, but the paper remains insufficient contact with the top run of the endless conveyor I6 so thatthe cross bars a will have sufiicient frictional grip on the paper todraw it gentlyforward through the drying zone. The endless conveyor isdriven at a speed materially greater than that at which the paperis togo through the drying zone, and the cross bars 54 will therefo're'slipfrictionally against the paper and so leave no visible stick marks Thecontact between stick and paper is so light that no marks are left evenif the paper is wafted'on theheated einmneumntezemrsut.srscontaetmsthsthezernss we constructinm ff wijdniy tissue;

the dryer ibejvaried smore-eor-ilesS'; in dil'maysbelfoot the-weight femer waterricontamed nyi-t:andrithertypeeoficoclrlesde shied. may

of the paper will stay at the wet: bulb-temper tuteofi somewherez-between 1360 and-- 120 P :F ant :a'veragevcase. TREK-"3G8"reachsthatemperatureior:2 or sari-steam midi-1 80i is not :i-zrim'ed hedryi g process: ems qthesrate-of-gdryingq annual may be ndtedithatalthough, "the ;air ateenpenatuseimayiheiafiof rettthestemperaturetheir-ate a. which. thepapempassesthmugh the-dryerqqr:byanakingthediiterent hwn-idities: and; ztempenaturesg nay .be

.proavided bmprovldipg tween more; s jparate' sets-er inlet. ducts. and4,1 and, it desired. separate sources ot heatedzainoselectedtemperatureswhich serveto: .introduce.a g ofdesired'characteristicssat .differ-tent sipoints'. along. a=thee'xtent of .thedrying chamber. Suitable instruments be -e p qycdrtormeasurezthe drynessof the paper and thus to indicate a proper control of the humidity. Itwill also berneten =thata uritheaecnstruction illustrated, the paper issubjected -.to a. "radually incrasedte'xnperatureas"it approach ducts l6and 41 and thereafter toa temperature. menswear tem. 1 be controlledbyfans to regulate the'ILhum-i'dity as. well. asstemperature of the airithrou'ghollteithe drying zone. 1

When the paper goes to the drying one from the sizing'bath, it maycontain about; 42% of moisture, but this is only a very slight amount ofwater due to the thinness of thej 'paper, and it is readily evaporated.It is desirable to dry out the water between the paper fibres but toleave the fibres with a normal moisturecontent.

g-iye-=a;,desiredlcontrolled drying curveteammatee "high; de o coc sleto :th ;.mne dry-inesta e; hen e the: ond oner: dryin the leanerwhileitissubstantially g and; while it :isunder; only a, sli h 1510 1 3litothe product of-a supe ior p oduct alsoice observed that theproportions of: Elna bath as well-as the nature f the in-.

gredientseuScdvmay-be varied widely within the knowled e zthoseslr d n tartlihe ross :bars 54 do not impart material-1 tepsipmfio the Wet paper;since the paper is-supe ported-t. .asubstantialextentby the air currentsfrom the sta gered: holes in the lowerwall as the paperapartially floatsor waves abovev conveyor; Oriits pressure thereon is reduced, throssbarsanove-alongrelative thereto as they; draw. thepaper jforward andthis sliding; move ment FdQfiSrliOt leave detrimental marks. The barsmove only;;slightly faster than the paper so:

. thepcross, sticks-slide only a slight distance, suchas a littlemorethan the spacingbetween two sticks,- pd-thus give a uniformappearance t as isproduced' by the slight 51 310- tie al. slidingcontact. The operator of the machine: may vary the float, condition ofthe. pa er by moving the-damper 50. In fact, the :may rest.. lig;htlyallof the time on the Qro s-. l1ars,iliut{because of;-the verylightfrictional {engagement with the paper, the 'bars will linrelativethereto; andany marks causedby til ores barswillbemade substantiallyuniform atqliigrtheszlength; oi the paper. Hence it will-not be.v.Hecessawt cut out. the stick marks W 1 have -.herelio;-;cr.eated sucha loss in the total am. nto the final-product.

fi neepthe paper is held substantially fiat and; horizontalaas;itpas'ses. through the drying zone the tension onthe paper is only'thatwhich is. reguired: to. pull it; along in :a horizontal position.dlsohthefl paper is-not. supported on the cross. bars to six-chairextent that it will sag between them so-fermiestoons or loops. Any suchwould prevent slippage of the cross sticks, EA-and. se-would ave markswhere h paper f;v

the-parseandy t mpa t.sufi i t fr io l r n thereo 439 38. that. thepaper will move along.

The total dryness of the paper is preferably about 3%, and it willordinarily be in the {neighborhood of 2% to 5% by weight oftotalfinoisture, which represents a dry condition lsuificient to holdthe cockle in the paper. This a dition of dryness of the paper is 'to beemphasized, since the paper must be substantially dry or in such acondition when it leaves the dryin game that the cookie will not bepulled out materially when the paper is thereafter subjected to tension,such as is involved in a winding operation, or in cutting the paper byknives and while under pressure. Some of'the cookie is lost or-.converted to a more subtle appearance during thesetnsioning andpressure stages, but such" hahge does not aifect the. utility and markety of the paper. However, because of this su sure or tension stage, it isall the;

through the drying zone. =is omitted, then the paper will pass over thebelt 65, and because of frictional drag on the If the conveyor l6.

very dry paper at this point, the belt will not injure or mark the paperbut will give a desired tension to move the paper forward While it isentirely supported on the lower air currents derived from the duct [8.Because of this method of fully or partially floating the paper while itis drying, I may dry it at a far greater speed than heretoforefeasible.It will also be understood that the ratesof movement of the feed andpressure rolls l4 and of the wind-up drum 22 and the associated rollsare suitably coordinated to insure that the paper is held loosely afterit leaves the drying zone and so does not tend to impose undesiredtension upon the drying paper. The wind-up roll may be run at a slightlyslower rate than that of rolls I4 so as to compensate for shrinkage inthelength of the paper.

It will now be appreciated that my method comprises impregnating a paperstrip of desired weight and texture with a suitable aqueous sizing andthen drying that paperin a substantially horizontal and fiat conditionto dry the paper and associated sizing under such controlled temperatureand humidity conditions as to procurrents from beneath andpreferablyalso from above, and these air currents may be so proportioned as toprovidea buoyant effect that tends to support some of the weight of thepaper, and this buoyancy'may be such as to insure that the paperfloatssubstantially fully during at least the first part of the dryingstage Where the paper is wet and weak in structure. Since'the paper isheld in this horizontal position, only a sniall degree of longitudinaltension is required'to move it lengthwise through the drying zone. Thisforcerequired to move the paper may be dis-- tributed throughout thelength of the drying zone as is the case where the paper is movedforward bythe cross sticks of an endless laddertype conveyor. Where thatconveyor is employed, the paper tends to lag behind the sticks and' thusthe sticks slip along the under side of the paper and do not leavenoticeable marks. If the paper, is fully floated on the heated aircurrent, then it is dragged forward by a suitable device engaging thepaper after it has been fully dried so that this propelling mechanismwill not destroy-the cookie. 'It is desirable that the paper be dried toa total water content of not over by weight and preferably less sothatthe cockle condition will not be materially destroyed duringsubsequent operations, such as slipping the paper into narrower stripsor winding it in a roll, but wide variations may be made in temperaturecontrol depending on the requirements of the papermaker. The heat fordrying the paper may be obtained from any suitable source of conductive,convective or radiant heat, such as" infra red electric light bulbs orother heating devices located above and below the straight run of thepaper in the drying zone, or such devices may be installed in theheating chamber where the steam pipes are located, or as desired-.'

Various modifications in this process will now 8; '1.Tne method ofmaking cockled paper comprising the steps of providing a strip of paperwhich isimpregnated with waterand a oockle stabilizing sizing,progressivelymoving the strip forward through a drying zone in:asubstantially ilatand horizontal position with the under side of thepaperstri'p located above aseriesof cross sticks moving longitudinallyforward in a. paper supporting position,blowing against, the undersideofthe paper and upwardly directedbuoyant currentof 'air' which preventsthe paper from adhering locally to and looping between the cross sticks,while controlling the rate of paper movement at bothsides of the dryingzone and maintainingthe paper under only suicient tension to move itforward without destroying the cockle, and evaporating the waterprogressively and shrinking the paper and causing the sizing tostabilize the cockle. l

2. The method of making cockled paper comprising the step'sofprovidingawet strip of paper impregnated with water and acockl'e'stabili'zing sizing, progressively feeding the paper stripforward into, through'andoutof a' drying zone in a substantiallyhorizontal and flat condition with theaid of traveling cross sticksthere beneath 'moving'longitudinallyforward faster than the strip andwhich frictionally engage and slip relative to the underside of thepaper strip, while supporting a part of the wet weight of the strip on abuoyant current of heated :air' projected upwardly between the sticksand against theunder side of the strip and subjecting the-strip to onlthat light surface frictional contact with the sticks and a longitudinaltensionwhich is sufli cient to move the partially floated paperhorizontally without destroying thecockled eiiect, and evaporating thewater and shrinking the paper and thus causingstabilization of thecookie by the sizing remaining therein.

' STEPHEN B. STAFFORD.

REFERENCES The following references are of record in the me of thispatent:

V UNITED STATES PATENTS Number Name Date 1,951,004 Willis Mar. 13,19.34:

